Cut off the tips of the outside leaves. Cut off the stem so that the artichokes sits level in the pot. Remove the soft leaves at the center of the artichoke until you can reach and scrape out the choke. Place the artichokes in the cold water with the lemon juice until ready to cook.
Bring to boil about 2 inches of water with the lemon slice, garlic clove. Place the artichokes in a steamer basket, cover and steam for 30 - 40 minutes. Test for doneness by removing a leaf midway to the center of the artichoke. When desired tenderness is achieved, remove and drain, top side down in a colander.
Over a low heat, melt the brie in the cream. When smooth, turn off the heat and add the egg yolk, whisking constantly. Stir in ¼ cup of the parmesan, thyme and 2 TBS almonds. Stir until well blended.
Place the artichokes in an oiled baking pan, fill the artichokes to over flowing with the sauce, sprinkle with the rest of the parmesan and the remaining almonds, then broil until golden brown.